Security Experts:

TCU Flaws Expose Cars to Remote Hacking

Vulnerabilities discovered by researchers in telematics control units (TCUs) from Continental, which are used by several major car manufacturers, can expose vehicles to local and remote hacker attacks.

McAfee security researchers Mickey Shkatov, Jesse Michael and Oleksandr Bazhaniuk disclosed the flaws last week at the DEF CON security conference.

A TCU is an embedded system used for wireless tracking and communications to and from a vehicle. According to an advisory by ICS-CERT, the McAfee researchers discovered two vulnerabilities affecting Continental TCUs that use Intel’s Infineon S-Gold2 (PMB8876) 2G baseband chipset.

The more serious of the flaws, tracked as CVE-2017-9633 and related to the temporary mobile subscriber identity (TMSI), allows a remote attacker to execute arbitrary code on the baseband radio processor of the TCU. This type of vulnerability was disclosed several years ago by Ralf-Philipp Weinmann of the University of Luxembourg in a paper on baseband attacks.

The second weakness, CVE-2017-9647, is a stack-based buffer overflow that allows an attacker with physical access to the TCU to execute arbitrary code on the baseband radio processor.

ICS-CERT said the security holes affect 2G services present in several BMW models manufactured between 2009 and 2010, Nissan Leaf from 2011 to 2015, some Ford plug-in hybrid (PHEV) models, and several Infiniti models produced between 2013 and 2016. The agency warned that proof-of-concept (PoC) exploits are available.

An attacker can exploit the vulnerabilities to disable a vehicle’s infotainment system or tamper with functional features, but the affected carmakers claim critical safety features are not impacted.

Starting with last year, Ford has been working on updating or disabling legacy 2G modems and believes only a limited number of vehicles are still affected. The company is investigating the issue and will take further steps if needed. BMW has confirmed the existence of the flaws and it plans on addressing the problem.

Nissan and its luxury car division, Infiniti, have issued technical service bulletins advising dealers to disable the 2G TCU on customers’ vehicles at no charge. The company said the 2G cellular service is no longer active in the U.S. and the TCU no longer performs any functions. Nevertheless, the manufacturer decided to initiate this campaign “out of abundance of caution to help prevent potential cybersecurity issues.”

Continental has also confirmed the existence of the flaws, but it has yet to identify a mitigation plan, ICS-CERT said.

UPDATE. McAfee researchers have published a blog post summarizing their findings.

Related: ICS-CERT Warns of CAN Bus Vulnerability

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Related: Cars Plagued by Many Serious Vulnerabilities

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.